Increased safety motors - protection type eEx (e)

Increased safety motors (type e) are category 2G equipment for use in zone 1. These motors are not flameproof and not built to withstand an internal explosion. The construction of such a motor is based on increased security against possible excessive temperatures and occurrence of sparks and arcs during normal operation and when a predictable error occurs. The temperature classification for increased safety motors is valid for both internal and external surfaces, and therefore, it is important to observe the stator winding temperature.

Non-sparking motors - protection type Ex (nA)

Non-sparking motors (type nA) are category 3G equipment for use in zone 2. These motors cannot by any means ignite a potential explosive atmosphere under normal operation, see figure 1.4.6.

Dust Ignition Proof (DIP)

Two types of Dust Ignition Proof motors exist: 2D/category 2 equipment and 3D/category 3 equipment.

2D/category 2 equipment

In order to avoid static electricity to cause ignition, the cooling fan on a category 2 DIP motor for use in zone 21 (area with potential danger of explosion) is made of metal. Likewise, to minimise the risk of ignition, the external ground terminal is subject to more severe demands of construction. The external surface temperature of the enclosure, which is indicated on the motor nameplate and corresponds to the running performance during the worst conditions allowed for the motor. Motors for use in zone 21 (areas with potential danger of explosion) have to be IP65 protected, that is completely protected against dust.

3D/category 3 equipment

The temperature indicated on a category 3 DIP motor for use in zone 22 (areas with minor danger of explosion) corresponds to the running performance under the worst conditions allowed for that specific motor. A motor for use in zone 22 has to be IP55 protected, that is protected against dust. The IP protection is the only difference between 2D/category 2 equipment and 3D/category 3 equipment.

Mounting (International Mounting - IM)

Three different ways of mounting the motor exist: foot-mounted motor, flange-mounted motor with free-hole flange (FF) and flange-mounted motor with tapped-hole flange (FT). Figure 1.4.8 shows the different ways of mounting a motor and the standards that apply for the mountings. The mounting of motors is stated according to the following standards:

• IEC 60034-7, Code I,

i.e. designation IM followed by the previously used DIN 42590 code

• IEC 60034-7, Code II

Enclosure class (Ingress Protection - IP)

The enclosure class states the degrees of protection of the motor against ingress of solid objects and water. The enclosure class is stated by means of two letters IP followed by two digits, for example IP55. The first digit stands for protection against contact and ingress of solid objects and the second digit stands for protection against ingress of water, see figure 1.4.9.

Drain holes enable the escape of water which has entered the stator housing for instance through condensation. When the motor is installed in a damp environment, the bottom drain hole should be opened. Opening the drain hole changes the motor's enclosure class from IP55 to IP44.

Frame size

Figure 1.4.11 gives an overview of the relation between frame size, shaft end, motor power and flange type and size. For motors in frame sizes 63 up to and including 315М, the relationship is specified in EN 50347. For motors with frame size 315L and larger, no standard covers this relation. The figure shows where on the motor the different values that make up the frame size are measured.

Flanges and shaft end comply with EN 50347 and IEC 60072-1. Some pumps have a coupling, which requires a smooth motor shaft end or a special shaft extension which is not defined in the standards.